ProjectSummary The goals of this Pathway to Independence Career Development proposal are to request support for training to develop expertise in cancer epigenetics while addressing the role of slow cycling cells and histone modifications in phenotype plasticity of highly resistant metastatic melanoma. K99/R00 support during this part of my career will be integral to my successful development as an independent cancer researcher.ThetrainingplanoutlinedinthisproposalwilltakeadvantageoftheextensiveresourcesatThe WistarInstitute,UniversityofPennsylvaniaaswellasTempleUniversity.Mytrainingwillalsobeguidedby senior personnel who have successfully mentored predoctoral, postdoctoral, and clinical fellows in academiccareers. The scientific portion of this proposal focuses on experimentally determining the molecular mechanism underlying phenotype plasticity and therapy resistance of invasive melanoma and the role of epigenetic changesinphenotypeplasticityandmaintenanceofslowcyclingcells.Theproposedstudiesarebasedon mypreviousfindingsthatasubsetofmelanomacells,whichexpressWnt5Aandp21,survivemultipletypes of stress by entering a slow-cycling, senescent-like state, but still invade and retain the ability to form metastases.MypreliminarydatasuggestSEDTB1expressioncorrelateswithaninvasivephenotypeinour humanmelanomacelllinesanddrivingnon-invasivemelanomacellstoamoreinvasivephenotype,through over expression of Wnt5A, increases SETDB1 expression. Expression of SETDB1, a histone methyltransferase, has been implicated in the silencing of tumor suppressor p16. p16 is expressed in melanocytes and early stages of melanoma but is lost during melanoma progression and this correlates withp21expressionandasenescent-likeresponsefollowingstress.Inmelanoma,hypermethylationduring tumorprogressionisobserved,whichmayblocktheexpressionofmultipletumorsuppressorgenes,butthe roleofspecificepigeneticchangesinphenotypeplasticityanddrugresistanceisstilllargelyunknown. Therefore,inlinewiththesedataIwillexplorethefollowingscientificaims:1)toelucidatethemechanism by which Wnt5A and p21 promote the maintenance of slow cycling stem-like cells;? and 2) to determine if histone modifications induced by SETDB1 promote phenotype plasticity and invasion in melanoma cells. The completion of the scientific aims in this proposal will develop my research skills and knowledge in cancerepigeneticswhiledelineatingthemechanismbywhichhighlyinvasiveresistantcellsevadestressto promotemelanomametastasisandtherapyresistance.